Everybody cries at one point or another, but have you ever considered why you shed tears?

Whether it's tears of sadness or tears of laughter, there doesn't seem to be much point in getting a wet face – even scientists are divided on the reasons for emotional tears. BuzzFeed spoke to some experts about it, and here's what they had to say.

1.Different kinds of tears have different functions.

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There are three types of tearing, says Robert Provine, a professor of neurobiology and psychology at the University of Maryland. "Basal tears" exist in our eyes all the time – they keep our eyes moist, improve the way our eyes work, and help to prevent infection.

We also have tears that act as a response to irritation – like when you cut an onion, for example. These "irritation tears" are stimulated by abrasion, inflammation, and disease.

But the function of the third type, "emotional tears", is a puzzle among scientists.

2.One theory about emotional tears is that they're about communicating with other humans.

Provine believes that emotional tearing came about as a result of humans having to interact with other humans in order to survive.

In his book Curious Behavior: Yawning, Laughing, Hiccupping, and Beyond (Harvard University Press, 2012) Provine talks about research he conducted that shows how tears make neutral faces appear sadder. In his experiment he investigated the idea that tears make sad faces look even more sad by digitally removing tears from images of human crying faces and asking participants to rate them for sadness.

The results were as expected. "Faces with tears removed look less sad, sometimes not looking sad at all, or perhaps looking awed," Provine tells BuzzFeed. He called the emotional impact of tears on others the "tear effect".

3.Tears might act as a signal to other people that you really need help.

Findings from a study published in the science journal Motivation and Emotion earlier this year showed that "people evaluate a tearful person as more in need of help and as more friendly". Interestingly, the study also showed that people appeared to feel "more connected" to a tearful person.

"[Tears] not only have a strong impact on the perception of the crying individual but ... also change behavioural intentions of observers," the researchers wrote.

4.But tears are not always genuine displays of emotion and can often be used in a manipulative way, even by very young children.

Kalu Singh, a now-retired counsellor at Cambridge University, tells BuzzFeed that from a young age children manage to work out that crying is a good way to get attention and so use the behaviour to their advantage.

“Crying, or even whimpering and withering, are good strategies to get what they want from their carers – attention, embrace, food, and occasionally revenge on other children,” he says.

And it’s not just children who use tears in a manipulative way. Adults can use crying to avoid or take a break from a difficult situation, for example. Singh said this can be seen during therapy. “It is hard to think while crying. Sometimes it is even hard to breathe when sobbing,” he says. “So crying gives one respite, a breather, from explanation or interrogation.”

5.Tears might also have some medicinal properties.

There may be some truth in the idea that having a good old cry when you're sad can make you feel better. Ruthie Smith, a senior psychotherapist who worked for the NHS for more than 10 years, says that when her patients cry they tend to feel much better afterwards.

"When people are very stressed or in a state of trauma, they become dissociated or disconnected from their feelings because they are concentrating on survival," she says. "In the work we do often people will cry and release the energy from their bodies and feel a lot calmer and more balanced."

6.Obviously, not all emotional tears are sad. Tears of joy or laughter could be to do with how our emotions are regulated.

“It seems that tears of joy come about in instances when a person is overwhelmed with strong emotion,” Oriana Aragón, a social psychologist at Yale University, tells BuzzFeed. “It could be that these tears help that individual to return to more manageable levels of emotion by mechanisms within that person’s physiology.”

However, Aragón suggests that tears of joy might also send a signal to onlookers that the person crying needs help with managing their emotions. Tears encourage onlookers to come to their aid, by putting an arm around them, or tapping them on the back, for example. “You can witness this comforting reaction in many online videos that feature people experiencing tears of joy,” she says.

7.However, it is still up for debate whether tears of joy even exist at all – happy tears might actually be an expression of sadness without us even realising it.

“Some scientists believe ‘tears of joy’ are actually the expression of latent or non-conscious experiences of sadness and/or helplessness,” Aragón says. “Which would make them actually no different than tears of sadness.”

However, Aragón’s research suggests that “tears of joy” are at least different in the way that people report experiencing them. “Some people do account crying because they feel positive emotions,” she says.

"Evidence suggests that humans are not the only animals to cry emotionally," Kim Bard, professor of comparative developmental psychology at the University of Portsmouth, tells BuzzFeed.

"It is clear that many primates have vocal and facial expressions that convey the same level of sadness or distress as those of humans when they cry. The only thing missing in other animals is the tears."

Although other animals have basal tears and irritation tears, there has only been anecdotal evidence for emotional tears. One such example happened in 2014 when wildlife conservationists said they saw tears roll down the face of an elephant who had been rescued after more than 50 years of being held in spiked chains.

There are lots of stories about animals such as elephants crying emotionally and with tears, but it’s difficult to prove since animals can’t speak to humans. "Of course it’s a grey area, with plenty of anecdotal evidence in animals to suggest otherwise," says Dr Nick Knight, a general practice trainee doctor with a special interest in lifestyle medicine. "The problem is proving it."

Our seemingly unique ability to cry with tears is probably due, he says, to the "evolved, complex neural connections between our brain’s emotional centre and the crying apparatus by our eye, called the lacrimal system".